add contact_uri as parameter (#426)

Co-authored-by: Paulo Albuquerque <paulo.albuquerque>

Author: pjalbuquerque

example/lib/src/register.dart

@@ -136,6 +136,7 @@ class _MyRegisterWidget extends State<RegisterWidget>
     settings.displayName = _displayNameController.text;
     settings.userAgent = 'Dart SIP Client v1.0.0';
     settings.dtmfMode = DtmfMode.RFC2833;
+    settings.contact_uri = 'sip:${_sipUriController.text}';
 
     helper!.start(settings);
   }

lib/src/sip_ua_helper.dart

@@ -163,6 +163,7 @@ class SIPUAHelper extends EventManager {
         uaSettings.sessionTimersRefreshMethod;
     _settings.instance_id = uaSettings.instanceId;
     _settings.registrar_server = uaSettings.registrarServer;
+    _settings.contact_uri = uaSettings.contact_uri;
 
     try {
       _ua = UA(_settings);
@@ -749,6 +750,7 @@ class UaSettings {
   String? displayName;
   String? instanceId;
   String? registrarServer;
+  String? contact_uri;
 
   TransportType? transportType;